Cardiovascular physiology
Left ventricular ejection fraction = (stroke volume / end diastolic LV volume ) * 100%
Stroke volume = end diastolic LV volume - end systolic LV volume
Pulse pressure:
Pulse pressure = Systolic Pressure - Diastolic Pressure
Factors which increase pulse pressure
1) a less compliant aorta (this tends to occur with advancing age)
2) increased stroke volume
Hypertention
Secondary causes:
A. Endocrine disorders:
1) primary hyperaldosteronism:
It is thought that between 5-10% of patients diagnosed with hypertension
have primary hyperaldosteronism, including Conn's syndrome.
This makes it the single most common cause of secondary hypertension.
2) phaeochromocytoma
3) Cushing's syndrome
4) Liddle's syndrome
5) congenital adrenal hyperplasia (11-beta hydroxylase deficiency)
6) acromegaly
B.Renal disease:
Accounts for a large percentage of the other cases of secondary hypertension
1) glomerulonephritis
2) pyelonephritis
3) adult polycystic kidney disease
4) renal artery stenosis
Other causes include:
1) NSAIDs
2) steroids
3) MAOI
4) pregnancy
5) the combined oral contraceptive pill
6) coarctation of the aorta
1
,Isolated systolic hypertension(ISH)
common in the elderly,
Affecting around 50% of people older than 70 years old.
The Systolic Hypertension in the Elderly Program (SHEP) back in 1991 established
that treating ISH reduced both strokes and IHD.
Drugs such as thiazides were recommended as first line agents.
This approach is contradicated by the 2011 NICE guidelines which recommends
treating ISH in the same stepwise fashion as standard hypertension.
Hypertension diagnosis:
NICE published updated guidelines for the management of hypertension in 2011.
Some of the key changes include:
classifying hypertension into stages
recommending the use of ambulatory blood pressure monitoring (ABPM) and home
blood pressure monitoring (HBPM)
Why were these guidelines needed?
It has long been recognised by doctors that there is a subgroup of patients whose blood
pressure climbs 20 mmHg whenever they enter a clinical setting, so called 'white coat
hypertension'. If we just rely on clinic readings then such patients may be diagnosed as
having hypertension when the vast majority of time there blood pressure is normal.
This has led to the use of both ambulatory blood pressure monitoring (ABPM) and home
blood pressure monitoring (HBPM) to confirm the diagnosis of hypertension. These
techniques allow a more accurate assessment of a patients' overall blood pressure. Not
only does this help prevent overdiagnosis of hypertension - ABPM has been shown to be
a more accurate predictor of cardiovascular events than clinic readings.
Blood pressure classification
This becomes relevant later in some of the management decisions that NICE advocate.
Stage Criteria
Stage 1 Clinic BP >= 140/90 mmHg and
hypertension subsequent ABPM daytime average or HBPM average BP >= 135/85 mmHg
Stage 2 Clinic BP >= 160/100 mmHg and
hypertension subsequent ABPM daytime average or HBPM average BP >= 150/95 mmHg
Severe Clinic systolic BP >= 180 mmHg, or
hypertension clinic diastolic BP >= 110 mmHg
2
,Diagnosing hypertension:
Firstly, NICE recommend measuring blood pressure in both arms when considering a
diagnosis of hypertension.
If the difference in readings between arms is more than 20 mmHg then the
measurements should be repeated.
If the difference remains > 20 mmHg then subsequent blood pressures should be
recorded from the arm with the higher reading.
It should of course be remember that there are pathological causes of unequal blood
pressure readings from the arms, such as supravalvular aortic stenosis.
It is therefore prudent to listen to the heart sounds if a difference exists and further
investigation if a very large difference is noted.
NICE also recommend taking a second reading during the consultation, if the first
reading is > 140/90 mmHg. The lower reading of the two should determine further
management.
NICE suggest offering ABPM or HBPM to any patient with a blood pressure ≥ 140/90
If however the blood pressure is >= 180/110 mmHg:
immediate treatment should be considered
if there are signs of papilloedema or retinal haemorrhages NICE recommend same
day assessment by a specialist
NICE also recommend referral if a phaeochromocytoma is suspected (labile or
postural hypotension, headache, palpitations, pallor and diaphoresis)
Ambulatory blood pressure monitoring (ABPM):
at least 2 measurements per hour during the person's usual waking
hours (for example, between 08:00 and 22:00)
use the average value of at least 14 measurements
If ABPM is not tolerated or declined HBPM should be offered.
Home blood pressure monitoring (HBPM):
for each BP recording, two consecutive measurements need to be
taken, at least 1 minute apart and with the person seated
BP should be recorded twice daily, ideally in the morning and evening
BP should be recorded for at least 4 days, ideally for 7 days
discard the measurements taken on the first day and use the average
value of all the remaining measurements
Interpreting the results
1) ABPM/HBPM >= 135/85 mmHg (i.e. stage 1 hypertension)
treat if < 80 years of age AND any of the following apply;
target organ damage,
established cardiovascular disease,
a 10-year cardiovascular risk equivalent to 20% or greater,
renal disease or diabetes
2) ABPM/HBPM >= 150/95 mmHg (i.e. stage 2 hypertension)
offer drug treatment regardless of age
3
, Hypertension management:
NICE published updated guidelines for the management of hypertension in 2011.
Some of the key changes include:
classifying hypertension into stages
recommending the use of ambulatory blood pressure monitoring (ABPM) and
home blood pressure monitoring (HBPM)
calcium channel blockers are now considered superior to thiazides
bendroflumethiazide is no longer the thiazide of choice
Managing hypertension
A. Lifestyle advice should not be forgotten and is frequently tested in exams:
1) A low salt diet is recommended, aiming for less than 6g/day, ideally 3g/day.
(The average adult in the UK consumes around 8-12g/day of salt)
2) A recent BMJ paper* showed that lowering salt intake can have a significant effect
on blood pressure. For example, reducing salt intake by 6g/day can lower systolic
blood pressure by 10mmHg
3) caffeine intake should be reduced
4) the other general bits of advice remain: stop smoking, drink less alcohol, eat a
balanced diet rich in fruit and vegetables, exercise more, lose weight
B. ABPM/HBPM >= 135/85 mmHg (i.e. stage 1 hypertension)
treat if < 80 years of age AND any of the following apply; target organ damage,
established cardiovascular disease, renal disease, diabetes or a 10-year
cardiovascular risk equivalent to 20% or greater
C. ABPM/HBPM >= 150/95 mmHg (i.e. stage 2 hypertension)
offer drug treatment regardless of age
For patients < 40 years consider specialist referral to exclude secondary
causes.
4
Left ventricular ejection fraction = (stroke volume / end diastolic LV volume ) * 100%
Stroke volume = end diastolic LV volume - end systolic LV volume
Pulse pressure:
Pulse pressure = Systolic Pressure - Diastolic Pressure
Factors which increase pulse pressure
1) a less compliant aorta (this tends to occur with advancing age)
2) increased stroke volume
Hypertention
Secondary causes:
A. Endocrine disorders:
1) primary hyperaldosteronism:
It is thought that between 5-10% of patients diagnosed with hypertension
have primary hyperaldosteronism, including Conn's syndrome.
This makes it the single most common cause of secondary hypertension.
2) phaeochromocytoma
3) Cushing's syndrome
4) Liddle's syndrome
5) congenital adrenal hyperplasia (11-beta hydroxylase deficiency)
6) acromegaly
B.Renal disease:
Accounts for a large percentage of the other cases of secondary hypertension
1) glomerulonephritis
2) pyelonephritis
3) adult polycystic kidney disease
4) renal artery stenosis
Other causes include:
1) NSAIDs
2) steroids
3) MAOI
4) pregnancy
5) the combined oral contraceptive pill
6) coarctation of the aorta
1
,Isolated systolic hypertension(ISH)
common in the elderly,
Affecting around 50% of people older than 70 years old.
The Systolic Hypertension in the Elderly Program (SHEP) back in 1991 established
that treating ISH reduced both strokes and IHD.
Drugs such as thiazides were recommended as first line agents.
This approach is contradicated by the 2011 NICE guidelines which recommends
treating ISH in the same stepwise fashion as standard hypertension.
Hypertension diagnosis:
NICE published updated guidelines for the management of hypertension in 2011.
Some of the key changes include:
classifying hypertension into stages
recommending the use of ambulatory blood pressure monitoring (ABPM) and home
blood pressure monitoring (HBPM)
Why were these guidelines needed?
It has long been recognised by doctors that there is a subgroup of patients whose blood
pressure climbs 20 mmHg whenever they enter a clinical setting, so called 'white coat
hypertension'. If we just rely on clinic readings then such patients may be diagnosed as
having hypertension when the vast majority of time there blood pressure is normal.
This has led to the use of both ambulatory blood pressure monitoring (ABPM) and home
blood pressure monitoring (HBPM) to confirm the diagnosis of hypertension. These
techniques allow a more accurate assessment of a patients' overall blood pressure. Not
only does this help prevent overdiagnosis of hypertension - ABPM has been shown to be
a more accurate predictor of cardiovascular events than clinic readings.
Blood pressure classification
This becomes relevant later in some of the management decisions that NICE advocate.
Stage Criteria
Stage 1 Clinic BP >= 140/90 mmHg and
hypertension subsequent ABPM daytime average or HBPM average BP >= 135/85 mmHg
Stage 2 Clinic BP >= 160/100 mmHg and
hypertension subsequent ABPM daytime average or HBPM average BP >= 150/95 mmHg
Severe Clinic systolic BP >= 180 mmHg, or
hypertension clinic diastolic BP >= 110 mmHg
2
,Diagnosing hypertension:
Firstly, NICE recommend measuring blood pressure in both arms when considering a
diagnosis of hypertension.
If the difference in readings between arms is more than 20 mmHg then the
measurements should be repeated.
If the difference remains > 20 mmHg then subsequent blood pressures should be
recorded from the arm with the higher reading.
It should of course be remember that there are pathological causes of unequal blood
pressure readings from the arms, such as supravalvular aortic stenosis.
It is therefore prudent to listen to the heart sounds if a difference exists and further
investigation if a very large difference is noted.
NICE also recommend taking a second reading during the consultation, if the first
reading is > 140/90 mmHg. The lower reading of the two should determine further
management.
NICE suggest offering ABPM or HBPM to any patient with a blood pressure ≥ 140/90
If however the blood pressure is >= 180/110 mmHg:
immediate treatment should be considered
if there are signs of papilloedema or retinal haemorrhages NICE recommend same
day assessment by a specialist
NICE also recommend referral if a phaeochromocytoma is suspected (labile or
postural hypotension, headache, palpitations, pallor and diaphoresis)
Ambulatory blood pressure monitoring (ABPM):
at least 2 measurements per hour during the person's usual waking
hours (for example, between 08:00 and 22:00)
use the average value of at least 14 measurements
If ABPM is not tolerated or declined HBPM should be offered.
Home blood pressure monitoring (HBPM):
for each BP recording, two consecutive measurements need to be
taken, at least 1 minute apart and with the person seated
BP should be recorded twice daily, ideally in the morning and evening
BP should be recorded for at least 4 days, ideally for 7 days
discard the measurements taken on the first day and use the average
value of all the remaining measurements
Interpreting the results
1) ABPM/HBPM >= 135/85 mmHg (i.e. stage 1 hypertension)
treat if < 80 years of age AND any of the following apply;
target organ damage,
established cardiovascular disease,
a 10-year cardiovascular risk equivalent to 20% or greater,
renal disease or diabetes
2) ABPM/HBPM >= 150/95 mmHg (i.e. stage 2 hypertension)
offer drug treatment regardless of age
3
, Hypertension management:
NICE published updated guidelines for the management of hypertension in 2011.
Some of the key changes include:
classifying hypertension into stages
recommending the use of ambulatory blood pressure monitoring (ABPM) and
home blood pressure monitoring (HBPM)
calcium channel blockers are now considered superior to thiazides
bendroflumethiazide is no longer the thiazide of choice
Managing hypertension
A. Lifestyle advice should not be forgotten and is frequently tested in exams:
1) A low salt diet is recommended, aiming for less than 6g/day, ideally 3g/day.
(The average adult in the UK consumes around 8-12g/day of salt)
2) A recent BMJ paper* showed that lowering salt intake can have a significant effect
on blood pressure. For example, reducing salt intake by 6g/day can lower systolic
blood pressure by 10mmHg
3) caffeine intake should be reduced
4) the other general bits of advice remain: stop smoking, drink less alcohol, eat a
balanced diet rich in fruit and vegetables, exercise more, lose weight
B. ABPM/HBPM >= 135/85 mmHg (i.e. stage 1 hypertension)
treat if < 80 years of age AND any of the following apply; target organ damage,
established cardiovascular disease, renal disease, diabetes or a 10-year
cardiovascular risk equivalent to 20% or greater
C. ABPM/HBPM >= 150/95 mmHg (i.e. stage 2 hypertension)
offer drug treatment regardless of age
For patients < 40 years consider specialist referral to exclude secondary
causes.
4
